An English boy who eats nothing but French fries, potato chips and the occasional piece of ham has been left blind due to the extreme vitamin deficiency in his diet, doctors in Britain said in a report published Tuesday. One of the doctors behind the article in the Annals of Internal Medicine personally treated the “fussy eater” from Bristol over the course of three years, and said he was previously healthy and took no medicines.

“His diet was essentially a portion of chips (fries) from the local fish and chip shop every day,” the doctor, Denize Atan, told CBS News partner network BBC News. “He also used to snack on crisps (chips) — Pringles — and sometimes slices of white bread and occasional slices of ham, and not really any fruit and vegetables.”

Atan said she first treated the boy at the age of 14, when he came in complaining of chronic tiredness. She diagnosed him with anemia and a deficiency in vitamin B12, along with copper, selenium and vitamin D. Atan gave the boy B12 injections and told him he’d have to start eating a more varied diet.

However, due to his “aversion to certain textures of food that he really could not tolerate… chips and crisps were really the only types of food that he wanted and felt that he could eat.”

The boy has what has been diagnosed since 2013 as “Avoidant/restrictive food intake disorder” (ARFID). Previously known as Selective Eating Disorder, it can be dismissed by parents as simply being fussy. But the health implications are very real, and they’re not limited to vision impairment.

As the doctors behind the article published on Tuesday note, “the risks for poor cardiovascular health, obesity, and cancer associated with junk food” are well known and often discussed, but when a diet heavy in such foods becomes one based entirely on them, the risks mount. The boy in Bristol was left malnourished, in spite of the fact that he ate every day and wasn’t hungry.

“He had lost minerals from his bone, which was really quite shocking for a boy of his age,” Atan told the BBC.

As for his eyes, he’s not completely blind and is still able to walk around on his own because he’s retained his peripheral vision. But with “blind spots right in the middle of his vision,” Atan said, he will never be able to drive, and “would find it really difficult to read, watch TV or discern faces.”